Greetings from the Roku Community, @Volscian!
To prevent your Roku TV from automatically changing the wallpaper, please try turning off the seasonal wallpaper and sponsored wallpaper by following the steps below:
- You can disable the Seasonal Wallpapers under Settings/Theme/Seasonal Wallpapers/[Off].
- Disabling Sponsored Wallpapers under Settings/Theme/Sponsored Wallpapers/[Off].
Hope you'll find this info useful.
Best,
The Roku Community Team
John
Roku Community Moderator